C#使用正则表达式删除行，包括换行符 [英] C# remove line using regular expression, including line break

问题描述

我需要从某些文本中删除与特定模式匹配的行.一种方法是使用带有开始/结束锚点的正则表达式，如下所示:

I need to remove lines that match a particular pattern from some text. One way to do this is to use a regular expression with the begin/end anchors, like so:

var re = new Regex("^pattern$", RegexOptions.Multiline);
string final = re.Replace(initial, "");

这很好，除了它留空行而不是删除整行(包括换行符).

This works fine except that it leaves an empty line instead of removing the entire line (including the line break).

为解决这个问题，我为换行符添加了一个可选的捕获组，但是我想确保它包括所有不同的换行符样式，所以我这样做是这样的:

To solve this, I added an optional capturing group for the line break, but I want to be sure it includes all of the different flavors of line breaks, so I did it like so:

var re = new Regex(@"^pattern$(\r\n|\r|\n)?", RegexOptions.Multiline);
string final = re.Replace(initial, "");

这可行，但是似乎应该有一种更直接的方法来做到这一点.是否有一种更简单的方法来可靠地删除整个行，包括结束换行符(如果有的话)?

This works, but it seems like there should be a more straightforward way to do this. Is there a simpler way to reliably remove the entire line including the ending line break (if any)?

推荐答案

要匹配任何单个换行符，可以使用(?:\ r \ n | [\ r \ n \ u000B \ u000C \ u0085 \u2028 \ u2029])模式.因此，您可以使用(?:\ r \ n | [\ r \ n \ u000B \ u000C \ u0085)代替(\ r \ n | \ r | \ n)?\ u2028 \ u2029])?.

To match any single line break sequence you may use (?:\r\n|[\r\n\u000B\u000C\u0085\u2028\u2029]) pattern. So, instead of (\r\n|\r|\n)?, you can use (?:\r\n|[\r\n\u000B\u000C\u0085\u2028\u2029])?.

详细信息:

• 000A -换行符 \ n
• 000B -线制表符
• 000C -一个换页符
• 000D -回车符， \ r
• 0085 -下一行字符， NEL
• 2028 -行分隔符char- 2029 -段落分隔符.

• ‎000A - a newline, \n
• ‎000B - a line tabulation char
• ‎000C - a form feed char
• ‎000D - a carriage return, \r
• ‎0085 - a next line char, NEL
• ‎2028 - a line separator char ‎- 2029 - a paragraph separator char.

如果要在匹配的行后删除任何0+个非水平(或垂直)空白字符，可以使用 [\ s-[\ p {Zs} \ t]] * :任何空格( \ s )，但(-[...] )水平空格(与 [\ p {Zs} \ t]匹配)代码>).请注意，由于某些原因， \ p {Zs} Unicode类别类与制表符不匹配.

If you want to remove any 0+ non-horizontal (or vertical) whitespace chars after a matched line, you may use [\s-[\p{Zs}\t]]*: any whitespace (\s) but (-[...]) a horizontal whitespace (matched with [\p{Zs}\t]). Note that for some reason, \p{Zs} Unicode category class does not match tab chars.

由于您正在使用 RegexOptions.Multiline 选项，因此必须在另一方面处理:它使 $ 匹配换行符( \ n )或字符串结尾.这就是为什么如果您的行尾是CRLF，则模式可能无法匹配.因此，在您的模式的 $ 之前添加一个可选的 \ r?.

One more aspect must be dealt with here since you are using the RegexOptions.Multiline option: it makes $ match before a newline (\n) or end of string. That is why if your line endings are CRLF the pattern may fail to match. Hence, add an optional \r? before $ in your pattern.

所以，要么使用

@"^pattern\r?$(?:\r\n|[\r\n\u000B\u000C\u0085\u2028\u2029])?"

或

@"^pattern\r?$[\s-[\p{Zs}\t]]*"

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